Braking device for elevating-trucks.



DE WIN 0. LAMBSON. BRAKING DEVICE FOR ELEVATING TRUCKS. APPLICATION FILED SEPT. 26. 19!].

Patented J une 11, 1918.

VEN To %W6. 'M m.

' ATTORNEYS.

WITNESS -nn rnn srArns PATENT OFFICE.

' Dn wrrr c. LAMBso or srnmcr nnn, MASSACHUSETTS, Assrcnon 'ro THE FISK RUBBER COMPANY, or cnicornn Farms, MASSACHUSETTS, A CORPORATION or mnssncnusnrrs.

To all whom z'fmay concern: i Be it known that I, DE WIT'r C..LAMBSON',

* a citizen of the United States, and a resident which the following is a specification.

, trucks must pass, and

wheels and is arranged; to

This invention relates to braking devices for .trucks, and

more .particularly to such devices as are adapted for use with lifting or elevating trucks.

Lifting trucks have come into extensive use infactories as an eflicient means of transferring loads from point to .point. F re.- quently, in factories there are numerous in clined runways, down. which the loaded heretofore, with trucks of the lifting type, it has been customary for the operator to hold back the load by'brute strength. Aside from .the effort necessary. on, the ,part of the operator to check the descent .-of the. truck, there is always thepossibility that a heavily loaded truck mayget away from the operator, whilepassing down steep inclines, and cause an accident. f 1

An object of this invention is to provide a braking mechanism designed for application to. atruck of the lifting type and particularly characterized by a improved actuating device involving a manually-operable leverwhich maybe moved to apply various degrees of braking ressure to the stay put in its moved positions without the necessity of specialholding means. v p H Another ob'ect ofthe, inventionis to pro- A, ,vide a braking mechanism fora truck of the liftingtype which may be operated only when the load lifting platform of the truck is in raised position ready for transportation of theload and which is arranged to permit therelatively large. degree of movement between the platform and wheel sup ported frame of the truck whenthe former is lowered, I v I Another objectfof the invention is to provide a generally simplified and improved mechanism for actuating abrake a ins aa ee em mii Specification of Letters Patent.

' BRAKIN DEVICE ron nLEvA'rING-rRUcKs.

Patented J nne 11,1918.

Application filed September 26, 1917. Serial No. 193,221.

Other objects andadvantages will appear in the following description and in the ap pended claims. t

The invention, in an embodiment at present preferred, is shown for illustrative purposes in the accompanying drawings, in which Figure 1 is a plan view of a truck embodying the invention;

F 'g. 2 is aside elevational view thereof; Fig. 3 is a fragmentary cross-sectional view taken on the line 33 of Fig. 1; and

Fig. 4 is a. sectional view taken on the line H of Fig. 3.

1 Referring to these drawings, a lifting truck has been indicated in conventional form in Figs. 1 and 2. The relatively stationary and relatively movable frames of the truck are designated a andb, respectively. The frame a :is supported by front and rear wheels 6 and d, respectively, and the frame I; or load lifting platform is supported from frame a through the intermediary of suitable lifting mechanism (not shown). The lifting mechanism has not been illustrated for the reason that. it; is unnecessary to an understanding of the invention. Such mechanism is well known to those skilled in the art and for the present purposes it will suflice to state that frame 6, which is illustrated in elevated position, may be lowered by. moving it toward-the right (Fig. 2) and may again be raised by moving it toward the left.

Mounted in and. extending between the two longitudinal members'of frame a is a cross-shaft 5 and loose on the latter and held to engage its wheel 01. Also fixed to sleeve 6 and upstanding therefrom is an arm 8 ,which is pivotally connected to a link 9.

The latter extends forwardly and at its for- ,ward end is provided with a slot 10. A

member 11, loosely mounted on a rod '12,

which in turn is slidably mounted in frame .b,'has a forked depending portion (see Figs. Q and 3) which encompasses the forward and 9 and the at??? s re e d-Fe extending forward member 11 by a pin 13 which is suitably fixed in member 11 and loosely passes through slot 10.

One end of rod 12 is threaded to receive nuts 1 1 against which the member 11 is forced by a coiled spring 15 (Fig. 1) which acts between the member and a transverselypart of frame 6. Fixed to the latter part and on the side opposite from spring 15 is a member 16 having on its In the operation of lifting trucks, the load lifting platform I) is always in raised position when the load thereon is to be transported from point to point. This condition is necessary for, as is well knowni'n the art, the load is supported on platforins having spaced legs between which the truck is positioned while its frame I) is in lowered position. The elevation of frame I) raises the platform suiiiciently so that its spaced legs clear the floor. It will be readily apparent that, with frame I) in raised position illustrated in Fig. 2, the brakes may be readily applied. Thus, if lever 18 is pulled upwardly, it will also be forced forwardly by the 'coaction of its cam surfaces with the surfaces 17, and rod 12 and member 11 will, therefore, be carried therewith. The forward movement of member 11 'cause'sa like movement of link 9 by reasonofthe'engagement of pin 13 with the left hand end of slot 10, whereby lever 8 is rocked 'to force shoes 7 against wheels 0?.

The connection between lever 8 and member 11 is arranged to permit frame 6 to be lowered without causing a movement of the brake shoes. Thus, when frame I) is lowered, it moves longitudinally to'the right (Fig. 2) and pin 13'moves idly to the right hand end of slot 110 without imparting movement to link 9. On account of the fact that the loaded truck is not transported when frame 6 is in lowered position, it is not necessary to provide means for applyingthe brakes lowered position. The arrangement, whereby frame b can be lowered without disturbing the position of the shoes 7, is particularly important in elevating trucks "for, as is well known, the frame a'and platform I) are purposely arranged-to lie closely adjacent the'fioor, and, therefore,

'there is but little room available for the mounting'of brakes. "Were .the' slot 1O omitted, the shoes 7 'wouldbe swung ina clockwhen the platform I) is lowextent that the lower ends of the shoes would dig into the floor. To shorten the shoes 7 sufficiently to avoid this difficulty would reduce to an undesirable extent the area of the shoes available for braking action on the wheels and then a longer lever 18 would be required, but this already is as long as is permitted by the standard construction of lifting trucks.

The special problems of mounting abr'ak'e system on truths of the lifting type have been solved by the expedient of the pin and slot connection its functional equivalent between the parts an frames (land I). The braking system has been articularly desighed to suit lifting trucks astonnne ly coi'i'str'ucted rather than to attempt modifi cation of the lifting" truck structure, which has been already developed into successful commercial and standardized form- A most important feature of the strueture described consists-in. the arrangement of the mechanism for actuating the brake shoes. Thismechanism is of alvaiit'ageously simple and "relatively inexpensive construction, and yet is highly efficient for the present use. The cam surfaces 17 and the "matin cam surfaces on lever 18 are so made that the latter stays put in any position to which it may bemoved. lhus-ythe inclinawise direction, ered, to such an tion of the cam surfacesis such-that spring 15 is not operable 'toturn the cam surfaces on lever l8'relativ'ely to the surfaces 17. This arrangement is important the-presentatiparatus inasmuch as it allows-the operator, just before he starts the truck-down anin cline-,-'to move lever 18'tobbtain the desired degree of braking pressure on wheels d. The truck may then safely pass down the in cline with little exertion on the part of the perator. 1 1t is'partieularly to be noted'that the lever '18 remains inthe position to'whi'ch it is moved without the provision of special holding means and, aside from 'the 'savin'g incident to the elimination of such means, there is the decided advantage that the "setting 'or releasing of the brakes is made easier and'inore convenient for the operator.

The invention has 'beendi-seieseu, in'ah embodiment at 'present I preferred, for the purposes of illustratiombut the scope ofthe invention is defined byt-he appended claims ratherthan bytheforegoing description.

I claimIisev p p p 1. The combination in'a'truck, of brake shoes movably mounted to engage wheels thereof, and "stationary and lever operated co'actin'g came so constructed that the lever operated team is movable axially when tur ed with "relati n to the stationary ca and "connections between the'lever and said shoes to force the latter against said whee-1s cam, said cams being so constructed that the lever operated cam remains in the positions to which it is moved.

2. In a lifting truck, a wheel supported frame, a load lifting platform movable relatively thereto, brake shoes pivotally mounted on the frame to swing into engagement with the rear wheels of the truck, a lever on the forward end of the platform, a pivotal support for said lever, connections between said support and shoes, and means operable to move the lever and support axially of the latter When the lever is swung on its pivotal support, the lever and said means being constructed and arranged so that the lever remains in positions to which it is moved, whereby the lever may be set to cause various degrees of braking pressure to be exerted on said wheels.

3. In a lifting truck, having a wheel supported frame and a load lifting platform movable relatively to the frame, brake shoes carried by the frame and adapted to engage wheels thereon, a power multiplying mechanism carried by the platform, and means connecting said shoes and mechanism, whereby an actuation of the latter will move the shoes against said wheeels, said mechanism comprising a cam on the platform, a rod passing through said cam and connected to the last-named means, a lever mounted on said rod and having a cooperating cam portion to engage said cam, and means to hold the said portion in engagement with the cam, whereby a swinging movement of said lever will move the rod and thus said shoes, said lever arranged to be frictionally held in the positions to which it is moved.

4. The combination in an elevating truck, having a wheel supported frame anda load lifting platform movable relatively to the frame, of braking means mounted on the frame and adapted to engage wheels thereon, actuating means carried by the platform, and means connecting the actuating and braking means, whereby an actuation of the former will cause the latter to exert a braking action on said wheels when the plat form is in raised position, the connecting means being constructed to permit the platform to be lowered without moving the braking means.

5. In a lifting truck, having a wheel supported frame and a load lifting platform movable relatively to the frame, brake shoes carried by the frame and movable to engage wheels thereon, a power multiplying mechanism carried by the platform and adapted for manual actuation, said mechanism including a slidable member, and a link connecting the latter to said shoes, said link and member having a pin and slot connection to prevent movement of the brake shoes when the platform is lowered relatively to the frame.

DE WITT C. LAMBSON.

Copies of. this patent may be obtained for five cents each, by addressing the Commissioner of Iatents, Washington, D. 0. 

